The REC1 and REC2 genes of the yeast-like fungus Ustilago maydis exert far- reaching control over DNA repair and recombination. The genes have been cloned, the DNA sequences have been determined, and the deduced amino acid sequences of the encoded proteins have been analyzed. The REC1 gene product is predicted to be a 3'-5' exonuclease. The REC2 gene product is predicted to be a recA-like homologous pairing protein. The gene products have been purified and overexpressed and direct biochemical analysis has confirmed the predicted gene functions. Proposed studies include further experimentation to explore the function of the proteins and to dissect the transcription units of the genes.